The present invention relates generally to methods and systems for cleaving optical fibers, and more particularly, for cleaving optical fibers for use with form factor connectors.
Optical fibers are frequently used in communications systems, generally, where light energy is transmitted very long distances with little or no energy losses. Devices coupled to optical fibers and coupling of optical fibers together require cutting and subsequent connecting of the optical fibers. Unacceptable loss of light energy at a coupling is detrimental to most transmissions and is consequently undesirable.
A junction between light fibers has generally a glass-to-glass interface where one fiber precisely abuts another fiber to minimize energy losses and signal distortions introduced at these junctions. Miles of optical fibers are installed in locations of varying conditions that demand tools to cleave optical fiber, which consistently provide acceptable cleaved fiber and ease of operation.
Conventional optical fiber assemblies include an optical fiber covered by a sheath. An end portion of the optical fiber of a first optical fiber assembly is typically joined to an end portion of the optical fiber of a second optical fiber assembly through the use of mating fiber optic connectors. When fiber optic connectors of a first category are used, the sheath of the end portion of the optical fiber assembly is removed to expose the optical fiber of the end portion as an unsheathed optical fiber. The unsheathed optical fiber is then inserted into a first category connector with the unsheathed optical fiber extending through a ferrule thereof. A portion of the sheathed optical fiber of the optical fiber assembly adjacent the unsheathed optical fiber is also inserted into the first category connector to securely fix the optical fiber assembly to the connector.
Conventional fiber cleavers are used to trim to a desired length the unsheathed optical fiber of the optical fiber assembly that extends beyond the ferrule of the first category connector after the optical fiber assembly has been securely fixed in the first category connector. First category connectors include ST, SC and FC connectors. A distinguishing feature of the first category connector is that the unsheathed optical fiber extending beyond the ferrule of the connector is trimmed after the optical fiber assembly is securely fixed in the connector.
One fiber cleaver illustrated in FIGS. 1 and 2 includes a housing assembly having an opening therein for receiving the ferrule of the first category connector and the unsheathed optical fiber to be trimmed. The fiber cleaver also has components within its housing assemblies configured to bend and cleave the unsheathed optical fiber Positioning components are disposed in close proximity to the opening of the housing assembly to control positioning of the ferrule and consequential positioning of the unsheathed optical fiber within the housing assembly leaving a predetermined, exposed miniscule length, Lm, of the unsheathed optical fiber extending beyond the ferrule after cleavage of a free end portion of the unsheathed optical fiber.
Due to construction details of conventional fiber cleavers, including use of such positioning components, the conventional fiber cleaver is suitable for only the first category of fiber optic connectors. There exists a second category of fiber optic connectors, such as small form factor connectors, including MTRJ connectors, that requires cutting of the unsheathed optical fiber of an optical fiber assembly to a desired length before the optical fiber assembly is securely fixed into the fiber optic connector. The conventional fiber cleaver designed for the first category fiber optic connector is not designed to cut the unsheathed optical fiber of an optical fiber assembly to proper length for use in the second category fiber optic connector. No readily apparent solution exists other than providing two different fiber cleavers for each technician in the field to handle both categories of fiber optic connectors or replacing the conventional fiber cleavers designed solely for the first category fiber optic connectors with more complicated dual purpose fiber cleavers for both categories of connectors. Either solution necessitates costly manufacture of many additional fiber cleavers.
The present invention resides in an adapter for use with a fiber cleaver configured to receive a connector ferrule and cleave an unsheathed optical fiber end portion of a first optical fiber assembly extending beyond the connector ferrule. The adapter includes a body having an insertion member configured to be received by the fiber cleaver in lieu of the connector ferrule. The insertion member contains a passageway for removably receiving an unsheathed optical fiber end portion of a second optical fiber assembly and has a passageway opening through which the unsheathed optical fiber end portion of a second optical fiber assembly extends for cleaving by the fiber cleaver while the adapter is received by the fiber cleaver. The passageway is configured to allow insertion into the adapter and removal from the adapter of the unsheathed optical fiber end portion of the second optical fiber assembly while the adapter remains received by the fiber cleaver.
One embodiment of the adapter is useable to convert a fiber cleaver constructed for use with a first category connector to cleave a fiber optic of a fiber optic assembly after inserted within the first category connector, to use with a second category connector to cleave the fiber optic prior to insertion within the second category connector, where the optical fiber assembly has an unsheathed fiber end portion extending beyond an end of a sheathed portion. When used with a first category connector having a connector ferrule with a passageway extending to a passageway opening at a distal end of the connector ferrule, the sheathed portion is inserted within the first category connector with the unsheathed fiber end portion extending through the connector ferrule passageway and out of the connector ferrule passageway opening and extending beyond the connector ferrule distal end.
The fiber cleaver has a housing chamber containing a stop and a housing opening having an end. The housing opening end is adjacent to and opens into the housing chamber proximate to the stop. The housing opening is sized to receive the connector ferrule therein and the stop is arranged to engage the connector ferrule distal end and hold the connector ferrule distal end at a predetermined position within the housing chamber against further movement into the housing chamber with the unsheathed fiber end portion extending beyond the connector ferrule distal end and into the housing chamber. The fiber cleaver has a cleave member within the housing chamber configured to cleave, without use of the adapter, the unsheathed fiber end portion extending out of the connector ferrule passageway opening to a first length extending beyond the connector ferrule distal end.
The adapter has a body with an insertion portion having a distal end. The insertion portion is sized to be removably received within the housing opening with the insertion portion distal end in engagement with the stop. The body has a passageway extending to a passageway opening at the insertion portion distal end. The body passageway sized to receive the fiber optic assembly therein. The body further includes means to hold the fiber optic assembly at a predetermined position within the body passageway with the unsheathed fiber end portion extending out of the passageway opening beyond the insertion portion distal end by at least the amount of the first length and into the housing chamber for cleaving by the fiber cleaver cleave member to a second length. The second length being measured while in the body passageway after cleaving as the sum of the length of the unsheathed fiber end portion extending beyond the end of the sheathed portion to the insertion portion distal end plus the amount of the first length.
In one embodiment the body passageway has a first lengthwise portion sized to receive the sheathed portion of the fiber optic assembly therein and a second lengthwise portion extending to the body passageway opening and sized to receive therein the unsheathed fiber end portion. The body further includes a stop, formed by the difference in width sizes of the body passageway first and second portions. The stop is arranged to engage the end of the sheathed portion when inserted into the body passageway first portion and hold the fiber optic assembly at the predetermined position within the body passageway against further movement toward the body passageway opening.
In the one embodiment, the adapter is used with the second category connector having a passageway sized to receive the sheathed portion of the fiber optic assembly therein with a lengthwise portion of a third length. The body passageway first portion is substantially the same length as the third length.
The body passageway first and second portions of the illustrated embodiment are coaxial.
One embodiment also shows the adapter arranged for use with the housing having an outward surface extending at least partially about an outward end of the housing opening. The body includes a head portion to which the insertion portion is rigidly connected and from which the insertion portion extends. The head portion has a width larger than a width of the insertion portion, and the insertion portion has a length to position the head portion proximate to the outward surface of the housing when the insertion portion is within the housing opening with the insertion portion distal end in engagement with the stop. The body passageway extends through the head portion and is lengthwise through the insertion portion, with the body passageway first portion being located within the head portion.
The embodiment shown can be used with the second category connector having a passageway sized to receive the sheathed portion of the fiber optic assembly therein with an interior stop to engage the end of the sheathed portion when inserted into the connector passageway and having a fiber stub with an inward end spaced away from the interior stop by a predetermined distance. When the unsheathed fiber end portion is cleaved by the cleave member of the fiber cleaver, a cleaved fiber end is produced. The second length is selected to extend the predetermined distance so as to position the cleaved fiber end adjacent to the inward end of the fiber stub when the sheathed portion of the fiber optic assembly is within the connector passageway with the end of the sheathed portion at about the interior stop.
The insertion portion of the adapter is shown with a width to fit snuggly within the housing opening.
The present invention also includes the combination of the above-described adapter with a fiber cleaver.
A method is also disclosed for using the adapter with the foregoing construction in conjunction with a fiber cleaver.
Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.